Is my old forklift gunna blow?

[Shadow_storm56]

We have an old toyota forklift that has many years and hours on it. Runs good except the ol blue smoke and the shutting off part. Compression is 175 in 3 cylinders and so high in cylinder number 3 that it blew up my Compression tester. I just put all new spark plugs in it so it just purrs and works like a top except the occasionally running out of oil part. Why does cylinder 3 have so much compression? Pretty sure that one is whare all my oil is going and thus the compression boost. It's high enough in that cylinder that if I disconnect all the spark plugs that cylinder will still start and run for 5-10 seconds and when the engines warmed up and you go to shut it off it will stay running really rough just dieseling on that 1 cylinder. Longest was 2 or more mins after tg3 key was off. So what I wonder is will this just keep going like this for a long time or eventually go boom and a rod end up in a bin of corn?

[tst]

take off the exhaust and do a compression check, if it is plugged up it could make high readings, are you sure your tester is good?

[Shadow_storm56]

take off the exhaust and do a compression check, if it is plugged up it could make high readings, are you sure your tester is good?

Tester was good, until I put it on the cylinder that diesels and it fired when trying to do the test so it kinda melted all the little parts in the gauge. I never got a reading on that one cylinder I just assumed it was really high since it's a gas engine and that cylinder can fire purely from compression.

[tst]

diesel engine can have up to 500 lbs of compression and fire by heat of the combustion, a normal tester would have heart failure if used on a diesel

[Shadow_storm56]

diesel engine can have up to 500 lbs of compression and fire by heat of the combustion, a normal tester would have heart failure if used on a diesel

When I say dieseling I mean running on just compression not actually having the same compression as a diesel. Haha well it did kill my compression tester but it didn't explode it just melted.

[Rick Spivey]

Not sure what all is going on with your engine....Normally, when a gas engine "diesels" after shutoff, it indicates that likely the timing is off, and/or the engine is running really hot (which bad timing can cause). You seem to have one cylinder that is acting up more than all the others, how did the spark plugs look when you replaced them? What color were they, and buildup or greasy residue, and did cylinder 3 look any different than the others? To answer your original question, if you do nothing, this engine will eventually break down; not sure it will go boom, it may just quit running and be impossible to start.

[Gary Dotson]

My guess is that your engine is dieseling because of glowing deposits in that combustion chamber. That and oil getting past the oil ring sealing the compression rings is also causing the artificially high compression reading in that cyl. Will it blow up? Who knows? You can reduce the dieseling by using an additive to dissolve some of the carbon deposit.

[tst]

yes check the timing, probably advanced to far and like Gary says it can build carbon, also if it idles to fast it can diesel

[Shadow_storm56]

Lots of good info , I should note only one cylinder diesels. The rest do not.

[john2189]

Is this gas or propane? I’m a retired Toyota lift truck mechanic. They are known for the intake manifold to carbon up. You have to soak it in a parts washer and clean it out.

[Shadow_storm56]

Is this gas or propane? I’m a retired Toyota lift truck mechanic. They are known for the intake manifold to carbon up. You have to soak it in a parts washer and clean it out.

It runs on gas but has the option for both. Well Jeeze intake manifold cleaning dosen't sound too bad

[john2189]

5r or 4y motor

[Shadow_storm56]

5r or 4y motor

It's 4 cylinder if that's what you mean

[Bill Hudson]

John is asking about the type motor it has.

Toyota has used its 4Y engine for forklifts with size capacities between 1.5 and 3.0 tons since early 1990s. Toyota forklifts with models proceeded with the number 42 all are equipped with the 4Y engine.

The Toyota Y engine is a design that's a combination of the Toyota T engine, and the Toyota R engine, ... The Y engine has mostly only been used in commercial and off-road vehicles.

Bill

[SONNY]

Sounds to me like carbon build up somewhere along the line. --- timing is probably o.k. --- just carbon causing the problem.